The present invention relates to a device of securing a film bearing indicia on the printing roll, and more particularly, to a device of securing a film bearing indicia on the printing roll in an automatic manner.
To explain the background of the present invention, reference will be made to FIGS. 1 and 2. The reference numeral 1 designates a printing roll, on which a film 2 bearing indicia 3 is placed. The film 2 has a first engager 4a at one end, and a second engager 4b at the other end, wherein the first engager 4a is engaged in a first recess 5 produced in the printing roll 1. The printing roller 1 has a catching means whereby the second engager 4b is caught so as to allow the film 2 to cover the printing roll 1. The catching means includes a groove 8, a rod 6 and a lengthwise recess 7 produced on the surface of the rod 6, as illustrated in FIG. 2. The rod 6 is rotable in the groove 8, thereby controlling the tension of the film 2 placed on the surface of the printing roll 1. The rod 6 has a extended boss at each end whereby the rod is rotated by means of a spanner 9. Although the detailed structure is not shown, it is arranged such that the rod 6 cannot rotate in the direction in which the film 2 becomes loose during the printing operation. When the film 2 is to be removed from the printing roll 1, the second engager 4b is disengaged from the recess 7.
This known device is disadvantageous in that at least two operators must attend to the placement of a film on the printing roll. One operator holds the film, and the other engages the film in the recess 7 while trying to stretch the film. In addition, a tool, such as a spanner or a driver, is required.